Diarrheal diseases are one of the major causes of human death worldwide. Strains of enterotoxigenic Escherichia coli (ETEC) that produce heat-stable enterotoxin (STa) are an important cause of diarrheal disease in humans and animals. They are responsible for a significant proportion of diarrheal cases among infants, travelers going from non-endemic to endemic areas and neonatal mammals. The development of effective strategies to reduce the incidence and severity of ETEC-caused diarrhea has been hampered by the lack of an effective vaccine or immunotherapeutic agents against this enteric pathogen. Thus, there is a need to develop vaccines and other pharmaceuticals for the treatment of diarrhea and diarrheal related diseases and disorders.